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Hydrogen adsorption and desorption from Cu(111) and Cu(211)
Kun Cao1, Gernot Füchsel, Aart W Kleyn
1Leiden Institute of Chemistry, Leiden University, P.O. Box 9502, Leiden, The Netherlands. l.juurlink@chem.leidenuniv.nl.
Physical Chemistry Chemical Physics : PCCP
|August 25, 2018
Summary
Hydrogen adsorption on copper surfaces shows lower sticking on stepped surfaces. This is due to higher activation barriers for dissociation on stepped copper (Cu(211)) compared to flat copper (Cu(111)) surfaces.
Area of Science:
- Surface Science
- Physical Chemistry
- Materials Science
Background:
- Understanding gas-surface interactions is crucial for catalysis and materials science.
- The reactivity of metal surfaces towards molecule adsorption and dissociation is influenced by surface structure.
- Molecular hydrogen adsorption on copper is a model system for studying dissociative adsorption.
Purpose of the Study:
- To investigate the effect of surface structure (flat vs. stepped) on hydrogen adsorption and desorption.
- To determine the role of step edges in the dissociative sticking probability of H2.
- To provide a combined experimental and theoretical understanding of H2 interactions with Cu(111) and Cu(211) surfaces.
Main Methods:
- Supersonic molecular beam experiments to measure sticking probabilities.
- Density Functional Theory (DFT) calculations to determine activation barriers.
- Temperature Programmed Desorption (TPD) spectroscopy for quantitative analysis.
Main Results:
- Stepped Cu(211) surfaces exhibit reduced dissociative sticking probability for H2 compared to flat Cu(111).
- DFT calculations reveal increased activation barriers for dissociation on stepped surfaces.
- TPD analysis indicates a lowered desorption barrier on Cu(211).
Conclusions:
- A-type steps on Cu(211) increase activation barriers to dissociation and lower desorption barriers for H2.
- Monoatomic steps significantly lower surface reactivity towards diatomic molecule dissociation.
- This study provides accurate low sticking probability data and resolves discrepancies in previous reactivity measurements.
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